Phenology and Morphology on a New Member of Japanese Gracilaria in Tosa Bay, Southern Japan

Changes in morphological characteristics and thallus fragmentation patterns of anew member of Japanese Gracilaria, G. lemaneiformis, were investigated. The Gracilaria species occurs in abundant quantities all year round on the coast of Uranouchi Inlet in Tosa Bay, southern Japan. This Gracilaria species occurs mainly in the form of fragmented thalli. The thalli were categorized into two types: fragments possessing a holdfast (A) and fragments without a holdfast (B). The maximum length attained by A-type thalli was 123±36cm in July, while the maximum length of B-type thalli (121±23 cm) was obtained in September. The highest occurrence of A-type thalli (25.41%) was in January. However, the B-type thalli occurred in greater proportions than the A-type thalli throughout the sampling period. Seasonal changes by fragmentation, mostly without holdfast, and free floating forms with no reproductive organs, are specific characteristics of this Gracilaria species in Japan that have not been found in other species of Gracilaria.